Actual moment of critique: I do think the author isn't taking enough time or emotion to allow Vivian's death to land. I know other people have already pointed this out as well, but seriously, Vivian deserves better.
I do appreciate that Heika was like "f*** waiting around, I'm just taking my granddaughter to my house, get on my level"
(And I'm going to say that the magic-evidence thing wasn't brought up by him immediately in case Vivian was threatened to write that note - it would only be useful if Beatrice actually forged it. Having magic reinforce that Vivian wrote it would not have helped the mood of the investigation)